The process of frying and baking starchy foods such as potatoes and bread causes the formation of potentially harmful amounts of a chemical listed as a probable carcinogen.

Swedish officials said they were so surprised by the information that they decided to make it public immediately, rather than wait for publication in a scientific journal.

The chemical, acrylamide, which is used industrially in the manufacture of some plastics, is also apparently formed by the heating of starches. Foods with especially high levels of the chemical included french fries, potato chips and crackers.

The governmental agency, following up on research by a group of scientists at Stockholm University, studied more than 100 foods bought in Swedish stores and restaurants and determined that “fried, oven-baked and deep-fried potato and cereal products may contain high levels of acrylamide.”

The high acrylamide levels were initially discovered during a University of Stockholm study at a factory that used them industrially.

A Food and Drug Administration official said that the agency had not reviewed the report but that it considered the source to be “credible.”

The Swedish report said that high doses of acrylamide have been shown to cause cancers and that “it seems reasonable to conclude that a significant number, perhaps several hundred, of the annual cancer cases in Sweden can be attributed to acrylamide.”

The U.S. Environmental Protection Agency describes acrylamide as white, odorless, flake-like crystals that are used mainly in treating drinking water and for industrial purposes and can cause cancer in people exposed to high levels for a long period.

Findings unveiled at a news conference called by the food administration showed that an ordinary bag of potato crisps may contain up to 500 times more of the substance than the top level allowed in drinking water by the World Health Organization (WHO).

WHO recommends one microgram (one-millionth of a gram) per litre as a maximum permitted for drinking water.

Researchers were surprised by the high levels found in both the workers and the people used for a control study. The Swedish government began testing acrylamide levels late last year and found that they were elevated in many starch-rich foods that had been baked or fried. They were not found, however, in raw or boiled foods, leading researchers to conclude they were formed.

June 25 — The World Health Organization began a three-day emergency meeting in Geneva today to evaluate the recent discovery that certain popular starchy foods, from potato chips to bread, contain a chemical that can cause cancer.

New research suggests that you may have one more reason to avoid deep-fried foods.

Never before has the agency assembled so many experts, so quickly, to evaluate food safety.

“This is not just another food scare. This is an issue where we find a substance that could give cancer, in foods, and in significant amounts,” Jorgen Schlundt, head of WHO’s Food Safety Program, told ABCNEWS’ John McKenzie.

The alarms were triggered in April with the announcement that scientists in Sweden had tested more than 100 food items and discovered that potato and cereal products that were fried, oven-baked and deep-fried may contain high levels of acrylamide, a chemical used to make plastics and dyes that has caused cancer in animals.

“It did come as a surprise because it has not been considered as a normal process that you would get acrylamide out of food,” said Schlundt.

Researchers say it’s all about heat. The higher the cooking temperature, the greater the levels of acrylamide.

Bread was found to contain 50 micrograms of acrylamide. Cereals, cookies and crackers, and potato chips: 160, 410 and 1,200, respectively.

Too Soon to Worry?

Since the Swedish study, scientists in several other European countries have tested many of these popular foods with similar results. But here in the United States, many researchers warn we don’t know enough about acrylamide to start worrying.

While acrylamide causes cancer in rats, there is no evidence it does the same in people.

“We put all our reliance upon a rat strain to predict how we’re going to respond. Sometimes they do predict it well and many times they do not,” said Edward Calabrese, director of the Northeast Regional Environmental Public Health Center at the University of Massachusetts, Amherst.

Some researchers point out that even if they prove acrylamide is a carcinogen in humans, they would then have to determine what level is dangerous.

“It’s going to take an awful lot of time and effort to tease out whether it has any carcinogenic effect on humans at the doses we’re getting,” said Stephen Sase of the department of veterinary physiology and pharmocology at Texas A&M University in College Station, Texas.

In the meantime, scientists at the World Health Organization meeting must decide whether they know enough about the risks to recommend changes in eating habits.

Some researchers say if you needed yet another reason to pass on the potato chips, now you’ve got it.